Key independent decryption of graphically encrypted images

Abstract

Cryptographically, an encryption algorithm should be strong enough so that one could not extract any information from encrypted data. A graphical encryption method proposed in [1] for the security of computer data is cryptanalysed in this paper. There are some regions left unchanged and clearly visible in graphically encrypted images. Key independent decryption of graphically encrypted images is proposed for recovery of intelligible information. Decryption scheme is based on neighbourhood similarity characteristics of adjacent pixels. Simulation results show that the decrypted images obtained by the proposed scheme are quite intelligible to understand. The graphical encryption method in present form is not suitable for security applications as encrypted images can be decrypted easily. © 2010 Springer-Verlag.